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1// (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)
2// (C) Copyright 2003-2007 Jonathan Turkanis
3// Distributed under the Boost Software License, Version 1.0. (See accompanying
4// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt.)
5
6// See http://www.boost.org/libs/iostreams for documentation.
7
8#ifndef BOOST_IOSTREAMS_AGGREGATE_FILTER_HPP_INCLUDED
9#define BOOST_IOSTREAMS_AGGREGATE_FILTER_HPP_INCLUDED
10
11#if defined(_MSC_VER)
12# pragma once
13#endif
14
15#include <algorithm> // copy, min.
16#include <boost/assert.hpp>
17#include <iterator> // back_inserter
18#include <vector>
19#include <boost/iostreams/constants.hpp> // default_device_buffer_size
20#include <boost/iostreams/categories.hpp>
21#include <boost/iostreams/detail/char_traits.hpp>
22#include <boost/iostreams/detail/ios.hpp> // openmode, streamsize.
23#include <boost/iostreams/pipeline.hpp>
24#include <boost/iostreams/read.hpp> // check_eof
25#include <boost/iostreams/write.hpp>
26#include <boost/mpl/bool.hpp>
27#include <boost/type_traits/is_convertible.hpp>
28
29// Must come last.
30#include <boost/iostreams/detail/config/disable_warnings.hpp> // MSVC.
31
32namespace boost { namespace iostreams {
33
34//
35// Template name: aggregate_filter.
36// Template parameters:
37// Ch - The character type.
38// Alloc - The allocator type.
39// Description: Utility for defining DualUseFilters which filter an
40// entire stream at once. To use, override the protected virtual
41// member do_filter.
42// Note: This filter should not be copied while it is in use.
43//
44template<typename Ch, typename Alloc = std::allocator<Ch> >
45class aggregate_filter {
46public:
47 typedef Ch char_type;
48 struct category
49 : dual_use,
50 filter_tag,
51 multichar_tag,
52 closable_tag
53 { };
54 aggregate_filter() : ptr_(0), state_(0) { }
55 virtual ~aggregate_filter() { }
56
57 template<typename Source>
58 std::streamsize read(Source& src, char_type* s, std::streamsize n)
59 {
60 using namespace std;
61 BOOST_ASSERT(!(state_ & f_write));
62 state_ |= f_read;
63 if (!(state_ & f_eof))
64 do_read(src);
65 std::streamsize amt =
66 (std::min)(n, static_cast<std::streamsize>(data_.size() - ptr_));
67 if (amt) {
68 BOOST_IOSTREAMS_CHAR_TRAITS(char_type)::copy(s, &data_[ptr_], amt);
69 ptr_ += amt;
70 }
71 return detail::check_eof(amt);
72 }
73
74 template<typename Sink>
75 std::streamsize write(Sink&, const char_type* s, std::streamsize n)
76 {
77 BOOST_ASSERT(!(state_ & f_read));
78 state_ |= f_write;
79 data_.insert(data_.end(), s, s + n);
80 return n;
81 }
82
83 template<typename Sink>
84 void close(Sink& sink, BOOST_IOS::openmode which)
85 {
86 if ((state_ & f_read) != 0 && which == BOOST_IOS::in)
87 close_impl();
88 if ((state_ & f_write) != 0 && which == BOOST_IOS::out) {
89 try {
90 vector_type filtered;
91 do_filter(data_, filtered);
92 do_write(
93 sink, &filtered[0],
94 static_cast<std::streamsize>(filtered.size())
95 );
96 } catch (...) {
97 close_impl();
98 throw;
99 }
100 close_impl();
101 }
102 }
103
104protected:
105 typedef std::vector<Ch, Alloc> vector_type;
106 typedef typename vector_type::size_type size_type;
107private:
108 virtual void do_filter(const vector_type& src, vector_type& dest) = 0;
109 virtual void do_close() { }
110
111 template<typename Source>
112 void do_read(Source& src)
113 {
114 using std::streamsize;
115 vector_type data;
116 while (true) {
117 const std::streamsize size = default_device_buffer_size;
118 Ch buf[size];
119 std::streamsize amt;
120 if ((amt = boost::iostreams::read(src, buf, size)) == -1)
121 break;
122 data.insert(data.end(), buf, buf + amt);
123 }
124 do_filter(data, data_);
125 state_ |= f_eof;
126 }
127
128 template<typename Sink>
129 void do_write(Sink& sink, const char_type* s, std::streamsize n)
130 {
131 typedef typename iostreams::category_of<Sink>::type category;
132 typedef is_convertible<category, output> can_write;
133 do_write(sink, s, n, can_write());
134 }
135
136 template<typename Sink>
137 void do_write(Sink& sink, const char_type* s, std::streamsize n, mpl::true_)
138 { iostreams::write(sink, s, n); }
139
140 template<typename Sink>
141 void do_write(Sink&, const char_type*, std::streamsize, mpl::false_) { }
142
143 void close_impl()
144 {
145 data_.clear();
146 ptr_ = 0;
147 state_ = 0;
148 do_close();
149 }
150
151 enum flag_type {
152 f_read = 1,
153 f_write = f_read << 1,
154 f_eof = f_write << 1
155 };
156
157 // Note: typically will not be copied while vector contains data.
158 vector_type data_;
159 size_type ptr_;
160 int state_;
161};
162BOOST_IOSTREAMS_PIPABLE(aggregate_filter, 1)
163
164} } // End namespaces iostreams, boost.
165
166#include <boost/iostreams/detail/config/enable_warnings.hpp> // MSVC.
167
168#endif // #ifndef BOOST_IOSTREAMS_AGGREGATE_FILTER_HPP_INCLUDED